Submittal Sheet

Table Of Contents

Functions

Function

EVR solenoid valves are designed on two dierent principles:

Direct operation

Servo operation

1. Direct operation (NC)

EVR 2 – EVR 3 are direct operated. The valves open directly for full ow when the armature (3) moves up into the

magnetic eld of the coil.

This means that the valves operate with a minimum dierential pressure of 0 bar. The seat plate is tted directly on

the armature (3) see Design and material.

Inlet pressure acts from above on the armature and the valve plate. Thus, the inlet pressure and spring force act to

close the valve when there is no current in the coil.

2. Servo operation (NC)

EVR 4 – EVR 22 are servo operated with a "oating" diaphragm (4) see Design and material. The pilot orice of

stainless steel is placed in the center of the diaphragm. The seat plate is tted directly to the armature (3) see Design

and material. When there is no current in the coil, the main orice and pilot orice are closed. The pilot orice and

main orice are held closed by the armature spring force and the dierential pressure between inlet and

outlet sides.

When current is applied to the coil, the armature is drawn up into the magnetic eld and opens the pilot orice. This

relieves the pressure above the diaphragm, i.e. the space above the diaphragm becomes connected to the outlet

side of the valve.

The dierential pressure between inlet and outlet sides then presses the diaphragm away from the main orice and

opens it for full ow. Therefore a certain minimum dierential pressure is necessary to open the valve and keep it

open. For EVR 4 – EVR 22 valves the minimum dierential pressure for safe operation is 0.03 bar.

When the current is switched o, the pilot orice is closed. Via the equalization holes in the diaphragm, the pressure

above the diaphragm rises to the same value as the inlet pressure and the diaphragm closes the main orice.

EVR 25, EVR 32 and EVR 40 are servo operated piston valves. The servo piston (16) see Design and material with

sealing face closes against the valve seat by means of the dierential pressure between inlet and outlet side of the

valve and the force of the compression spring. When the coil is switched on, the pilot orice opens. This relieves the

pressure on the piston spring side of the valve. The dierential pressure will then open the valve. The minimum

dierential pressure for safe operation is 0.2 bar.

EVR (NO) has the opposite function to EVR (NC), i.e. it is open with de-energized coil. EVR (NO) is available with servo

operation only.

2.1. Bi-ow operation

Bi-ow operation with EVRC EVRC is a servo operated solenoid valve with a special diaphragm with built-in non-

return valve. The valve is for use in liquid lines in refrigeration plants.

EVRC allows ow in both directions and can be used in liquid lines in refrigeration plants with hot gas or gas defrost.

During the refrigeration period EVRC works as a normal solenoid valve, while during defrost it allows the condensed

liquid to return to the liquid manifold.

During the defrosting period the coil for EVRC must be energized.

2.2. Manual stem operation for EVR 6 - EVR 25 NC

EVR 6 - EVR 25 NC are available with optional manual stem operation to manually force the NC valve open when the

coil is de-energized.

Solenoid valve, Type EVR 2 - EVR 40